The overall goal of this application is to evaluate protocols important for the exploitation of ART that can enhance the propagation of NHP models of human disease. The use of ART to produce embryos from genetically valuable animals can contribute to a wide range of studies related to human health, from infertility to degenerative diseases. However, the current state of basic ART procedures in NHPs, such as embryo transfer and production of identical twins, is poor. Few studies have been devoted to improving these procedures. The proposed research will routinely produce embryos from rhesus monkeys using standard in vitro fertilization and embryo culture protocols in order to evaluate several different technical approaches to improve the production of animals for health related research. The aims of this resource development application are to evaluate: 1) strategies (number and stage of embryos) for transferring embryos to recipient females, in order to improve the success rate in producing offspring; 2) cross-species embryo transfer in macaques, in order to facilitate intra-uterine transfers; 3) the effectiveness of simple methods of blastomere separation or embryo splitting to produce identical twins; 4) a procedure for producing multiple embryos in vivo by superovulation and uterine flushing, thus avoiding possible artifacts from culturing in vitro produced embryos; and 5) preimplantation genetic diagnosis as a tool for selecting macaque embryos with specific genetic characteristics prior to embryo transfer, as a means to increase the efficiency of ART for propagating genetically valuable animals. By combining several of these technologies, the investigators will enhance the efficacy and utility of NHPs for health-related research, increase the fecundity of genetically-valuable animals, and improve the ability to select for specific genetic characteristics when breeding NHPs.